Catalysis Today, Vol.360, 12-19, 2021
Hydroisomerization of n-hexane over Pt/WOx-ZrO2-TiO2 catalysts
The role of TiO2 as an additive in the Pt/WO3-ZrO2 catalyst system over the catalytic activity in the hydroisomerization of n-hexane was investigated. The Pt/WO3-ZrO2-TiO2 catalysts were synthesized by two steps: the first step consisted in the WOx-ZrO2-TiO2 mixed oxides synthesis by the coprecipitation technique, and in a second step the Pt was incorporated by impregnation. The mixed oxides were characterized by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), nitrogen physisorption, scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The results showed that the synthesis method could promote a higher interaction among TiO2, WOx species and ZrO2 at 700 degrees C, producing WOx clusters that improve the n-hexane hydroisomerization conversion, TOR values and yields to bi-ramified components compared to the blank catalysts. The results confirmed the relationship among the surface area, tungsten content, and calcination temperature necessary to reach the formation of WOx species with the adequate domain size to stabilize the proton and form Bronsted acid sites. The incorporation of TiO2 mainly promotes the stabilization of these active sites.